test-drivers/vidtv/vidtv_ts.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * The Virtual DVB test driver serves as a reference DVB driver and helps
0004  * validate the existing APIs in the media subsystem. It can also aid
0005  * developers working on userspace applications.
0006  *
0007  * Copyright (C) 2020 Daniel W. S. Almeida
0008  */
0009
0010 #ifndef VIDTV_TS_H
0011 #define VIDTV_TS_H
0012
0013 #include <linux/types.h>
0014
0015 #define TS_SYNC_BYTE 0x47
0016 #define TS_PACKET_LEN 188
0017 #define TS_PAYLOAD_LEN 184
0018 #define TS_NULL_PACKET_PID 0x1fff
0019 #define TS_CC_MAX_VAL 0x0f /* 4 bits */
0020 #define TS_LAST_VALID_PID 8191
0021 #define TS_FILL_BYTE 0xff /* the byte used in packet stuffing */
0022
0023 struct vidtv_mpeg_ts_adaption {
0024     u8 length;
0025     struct {
0026         u8 extension:1;
0027         u8 private_data:1;
0028         u8 splicing_point:1;
0029         u8 OPCR:1;
0030         u8 PCR:1;
0031         u8 priority:1;
0032         u8 random_access:1;
0033         u8 discontinued:1;
0034     } __packed;
0035     u8 data[];
0036 } __packed;
0037
0038 struct vidtv_mpeg_ts {
0039     u8 sync_byte;
0040     __be16 bitfield; /* tei: 1, payload_start:1 priority: 1, pid:13 */
0041     struct {
0042         u8 continuity_counter:4;
0043         u8 payload:1;
0044         u8 adaptation_field:1;
0045         u8 scrambling:2;
0046     } __packed;
0047 } __packed;
0048
0049 /**
0050  * struct pcr_write_args - Arguments for the pcr_write_into function.
0051  * @dest_buf: The buffer to write into.
0052  * @dest_offset: The byte offset into the buffer.
0053  * @pid: The TS PID for the PCR packets.
0054  * @buf_sz: The size of the buffer in bytes.
0055  * @continuity_counter: The TS continuity_counter.
0056  * @pcr: A sample from the system clock.
0057  */
0058 struct pcr_write_args {
0059     void *dest_buf;
0060     u32 dest_offset;
0061     u16 pid;
0062     u32 buf_sz;
0063     u8 *continuity_counter;
0064     u64 pcr;
0065 };
0066
0067 /**
0068  * struct null_packet_write_args - Arguments for the null_write_into function
0069  * @dest_buf: The buffer to write into.
0070  * @dest_offset: The byte offset into the buffer.
0071  * @buf_sz: The size of the buffer in bytes.
0072  * @continuity_counter: The TS continuity_counter.
0073  */
0074 struct null_packet_write_args {
0075     void *dest_buf;
0076     u32 dest_offset;
0077     u32 buf_sz;
0078     u8 *continuity_counter;
0079 };
0080
0081 /* Increment the continuity counter */
0082 void vidtv_ts_inc_cc(u8 *continuity_counter);
0083
0084 /**
0085  * vidtv_ts_null_write_into - Write a TS null packet into a buffer.
0086  * @args: the arguments to use when writing.
0087  *
0088  * This function will write a null packet into a buffer. This is usually used to
0089  * pad TS streams.
0090  *
0091  * Return: The number of bytes written into the buffer.
0092  */
0093 u32 vidtv_ts_null_write_into(struct null_packet_write_args args);
0094
0095 /**
0096  * vidtv_ts_pcr_write_into - Write a PCR  packet into a buffer.
0097  * @args: the arguments to use when writing.
0098  *
0099  * This function will write a PCR packet into a buffer. This is used to
0100  * synchronize the clocks between encoders and decoders.
0101  *
0102  * Return: The number of bytes written into the buffer.
0103  */
0104 u32 vidtv_ts_pcr_write_into(struct pcr_write_args args);
0105
0106 #endif //VIDTV_TS_H